Fluid flow variation in a fluid line causes pressure variation in the fluid which can establish a resonant condition of standing pressure waves along the length of a fluid filled line due to waves reflecting from the ends of the fluid line. Fluid flow variation may be caused by a device moving fluid in the fluid line, such as when the fluid is excited by an input flow variation produced by a pump with sinusoidal motion of its pistons. Hydraulic lines, for example, resonate at their natural frequency with little excitation similar to an organ pipe. A standing wave is formed at the resonant frequency, creating pressure oscillations in the hose or tube forming the fluid line, or combination of hose and tube forming the fluid line. Hydraulic pumps provide excitation at a frequency equal to pump revolutions per minute (rpm) times the number of pump pistons. If the pump discharge line natural frequency is near this pumping frequency, a resonance will result. Pressure pulses created by the resonant condition can cause failures in hoses, fittings and clamps. Resonance pressure pulses within a hose causes hysteresis heating of the rubber/elastic parts of the hose and concomitant damage from the temperature excursions.
Methods available today are to change the tube length or diameter to change its resonant frequency. Often this is impractical due to physical constraints of location for the tube, the tube routing, friction loss if the tube is too small, or excessive weight if made larger. Resonating tubes are restrained by clamps and end fittings which can sustain damage and come loose when resonating tubes vibrate. Leakage and system loss have been experienced due to these effects. Additionally a Helmholtz type resonator can be added and tuned to the resonant frequency attempting to dampen a narrow range of oscillation. This method is only partially effective and can result in an improved condition but the basic problem remains.